Family:     Orchidaceae (orchid family)

Duration:  Perennial

Height:     15 - 61 cm (6 - 24 in)

Blooming: April - June


Pink Lady's Slipper Orchid

Cypripedium acaule  Aiton

Stem: erect, slender, and covered in small bristly hair.


Flowers: a single flower for each plant.  They are hot pink to almost a white with a pinkish tinge.  The flower has a very large labellum (a large petal that often forms a sort of lip) that looks like a slipper.

Leaves: 2 fairly large basal leaves that can grow up to 30 cm (12 in) x 15 cm (6 in).  There are no teeth on the leaves.  The bottom side of the leaf is silver with short hairs that have glands on them.

Fruit: a single, hairy capsule that turns from green to brown.

Sun: Part shade to shade.

Habitat: well-aerated, acidic soils.  Sphagnum bogs to mesic coniferous-deciduous forests.



Bonap map - Cypripedium acaule

Consortium of Midwest Herbaria - Cypripedium acaule

Michigan Flora - Cypripedium acaule

Argue, C.L., 2011. The Pollination Biology of North American Orchids: Volume 1: North of Florida and Mexico (Vol. 1). Springer Science & Business Media. pp. 202.

Comments: Pink lady's slipper orchids are one of the most showy orchids in Indiana.  You can see them on guided hikes at the Indiana Dunes National Park's Pinhook Bog.  This loud orchid is listed in Indiana as rare or uncommon with a place on Indiana's watch list

The pink lady's slipper can reproduce through self-pollination; however, it prefers to outcrossing.  Their main pollinator are the bumblebees (Bombus).  The construction of the flower makes it quite difficult for the pollinator to leave.  This ensures that the pollinator gets the pollen.  Even so, pollinator visits are usually infrequent making hand pollination the best approach to guarantee cross pollination.

Etymology: The genus, Cypripedium, is derived from two Greek words.  Cypris refers to the Greek goddess of love and beauty and pedis means foot or sandal.  Acuale is Latin for not having a stem.  Another common name for the pink lady's is the stemless lady's slipper.

C. acaule pinhook.JPG
Cypripedium acaule - Pinhook bog.JPG
Cypripedium acaule

all photos by Nathanael Pilla

Species Present and Native